When an image is picked up using a camera equipped with an XY-address scan type imaging device such as a complementary metal oxides semiconductor (CMOS) imaging device under illumination of a fluorescent light, stripe brightness unevenness or color unevenness occurs in a video signal. This phenomenon is referred to as flicker. This flicker is caused due to a fluorescent light connected to a commercial power supply (AC) repeating blinking basically with a cycle double a cycle of a power-supply frequency and due to operating principle of the imaging device.
A stripe brightness change pattern extending in a horizontal direction appears in an image in which flicker occurs. For example, when a moving image is observed, a stripe pattern appearing vertically is observed. Examples of related art which discloses a technique for suppressing such flicker include, for example, Patent Literature 1. Patent Literature 1 discloses a method for removing a flicker component included in an image by extracting the flicker component from the image, calculating a flicker correction coefficient which has a reversed-phase pattern of the flicker component and performing correction by multiplying a pixel value of the image by the flicker correction coefficient.